This invention is concerned with conveying continuous filter material, particularly filter material used in the manufacture of continuous filter rod of the tobacco industry.
It is known to deliver continuous filter material, e.g. crimped celullose acetate filter tow, from a bale or other source through conditioning apparatus, e.g. a tow opening device, to a further processing apparatus, e.g. a machine for converting the material into a continuous filter rod. In the conditioning apparatus the material may be moved past a plurality of conveying means which move at different speeds. The conveying means engage the filter material and, due to their different speeds, tend to stretch the material or allow it to contract under its own elasticity. Such as arrangement is commonly used to open or bloom crimped filter tow. The conditioning apparatus may also include a chamber or other device for applying plasticiser to the filter material. A typical conditioning apparatus of this type is Molins T05 machine and typical further processing apparatus comprises Molins PM5N filter rod making machine.
The conditioning apparatus may include first conveying means driven at an appropriate speed to withdraw and meter the filter material from its source, and second conveying means driven at an appropriate speed to deliver the material to the processing apparatus. The first and second conveying means may operate at different speeds and means may be provided for adjusting or setting these speeds. In a conventional arrangement the first and second conveying means are driven from the main drive of the processing apparatus by means of a variable speed transmission. This includes first means for varying the speed of the first and second conveying means and second means for varying the speed of the first conveying means. Thus it is possible to vary the overall speed of the conditioning apparatus relative to that of the processing apparatus, and also to vary the speed of the first conveying means relative to that of the second conveying means. The known arrangement has the disadvantage, however, that adjustment of the first varying means to change the speed of the second conveying means, which controls delivery to the processing apparatus, will also change the speed of the first conveying means, which meters the material into the conditioning apparatus, so that it is necessary to make a further adjustment of the second varying means if it is required to maintain the speed of the first conveying means. This can be an inconvenience, particularly when setting up the conditioning apparatus for a new type of filter material. A further disadvantage of this known drive arrangement is that the tension of the filter material between the first and second conveying means cannot be primarily controlled without affecting the speed of the first conveying means.